A couple ideas. The easiest is to get some Rust-Oleum Rust Reformer. It converts the rust to a paintable surface that is supposed to keep the rust from coming through. It is a cheap solution. If you want to go pro - get some POR 15 (it is alot more expensive but works better.) Don't just rattle can it, unless you sand all the rust out, and prime it first. If you don't get rid of the rust it will just come back.

Interesting take on it. I have been able to solve many of these problems by fixing the troughs too. This instructable is for when that doesn't work; which is fairly often. Lots of times, I run into a unit where the flow rate is fine, the troughs are open but the pads are still dry. In these situations, this fix has done the trick. I had to do it on 10 units on a commercial building after trying to open up the slots. We had great flow on the units from about 10 am until noon, and then after that, it was so hot, that the water wouldn't make it to the bottom of the pads, even though it was flowing correctly. So I agree, that the first pass is to check your flow, your slots and make sure everything is running correctly. This will solve it 80-90% of the time. When/if that doesn'...

Interesting take on it. I have been able to solve many of these problems by fixing the troughs too. This instructable is for when that doesn't work; which is fairly often. Lots of times, I run into a unit where the flow rate is fine, the troughs are open but the pads are still dry. In these situations, this fix has done the trick. I had to do it on 10 units on a commercial building after trying to open up the slots. We had great flow on the units from about 10 am until noon, and then after that, it was so hot, that the water wouldn't make it to the bottom of the pads, even though it was flowing correctly. So I agree, that the first pass is to check your flow, your slots and make sure everything is running correctly. This will solve it 80-90% of the time. When/if that doesn't work then you can try this one. If you set everything up correctly, this is a great fix in these situations.

The best thing to do is to take a look at what is happening inside. Take one of the panels off and see. Sometimes the fan is spinning too fast, but lots of times, the hoses aren't filling the troughs correctly and water is spilling or splashing. Try that and see how it goes.

Also, On this one, I put the biggest one they had at home depot. It was the 110,000 one and It couldn't really keep up. If you could get a bigger one, you probably will still want to increase the number of distribution tubes.

At somewhere between 94 and 97 degrees, most coolers can't keep the pads wet enough to provide cooling. As a result, they stop working well. It is a problem for thousands and thousands of swamp coolers. It is a well documented fact supported here by the many successful implementations of this idea, as well as other ideas aimed at keeping the pads wet at high temperatures.Some coolers and owners are able to do a better job of keeping the pads wet, but most lose effectiveness over time. The loss of performance may simply be due to incorrect pads, scaling of pads, undersized pump, or lack of maintenance. However, many of these units also suffer from design flaws and manufacturing defects such as: poorly placed or aligned output tubes, undersized pumps, water distribution channels tha...

At somewhere between 94 and 97 degrees, most coolers can't keep the pads wet enough to provide cooling. As a result, they stop working well. It is a problem for thousands and thousands of swamp coolers. It is a well documented fact supported here by the many successful implementations of this idea, as well as other ideas aimed at keeping the pads wet at high temperatures.Some coolers and owners are able to do a better job of keeping the pads wet, but most lose effectiveness over time. The loss of performance may simply be due to incorrect pads, scaling of pads, undersized pump, or lack of maintenance. However, many of these units also suffer from design flaws and manufacturing defects such as: poorly placed or aligned output tubes, undersized pumps, water distribution channels that don't allow for good water flow, etc. It is for these problems that I wrote this instructable.In addition, it is a verifiable fact that the effectiveness of a swamp cooler decreases as the relative humidity increases, not a myth. It is just one of those pesky laws of physics that we haven't been able to overturn yet. At a 106 degree outside to get 70 degree air, you will need to be less then 5% humidity. On the day of your post, you had a low of 7% humidity in Acton, so it seems probable that you would be blowing approximately 72-74 degree air with an outside temp of 106. If, for example, you were at 35% humidity on that day, you would only be blowing 88 degree air.This is why you don't see swamp coolers in the southeast US very often. It becomes more economic to just use a normal air conditioner when the humidity is up over 25% during the heat of the day.Hopefully this explanation will be helpful to people. You can google how swamp coolers work for some good articles on the subject.

At somewhere between 94 and 97 degrees, most coolers can't keep the pads wet enough to provide cooling. As a result, they stop working well. It is a problem for thousands and thousands of swamp coolers. It is a well documented fact supported here by the many successful implementations of this idea, as well as other ideas aimed at keeping the pads wet at high temperatures.Some coolers and owners are able to do a better job of keeping the pads wet, but most lose effectiveness over time. The loss of performance may simply be due to incorrect pads, scaling of pads, undersized pump, or lack of maintenance. However, many of these units also suffer from design flaws and manufacturing defects such as: poorly placed or aligned output tubes, undersized pumps, water distribution channels tha...

At somewhere between 94 and 97 degrees, most coolers can't keep the pads wet enough to provide cooling. As a result, they stop working well. It is a problem for thousands and thousands of swamp coolers. It is a well documented fact supported here by the many successful implementations of this idea, as well as other ideas aimed at keeping the pads wet at high temperatures.Some coolers and owners are able to do a better job of keeping the pads wet, but most lose effectiveness over time. The loss of performance may simply be due to incorrect pads, scaling of pads, undersized pump, or lack of maintenance. However, many of these units also suffer from design flaws and manufacturing defects such as: poorly placed or aligned output tubes, undersized pumps, water distribution channels that don't allow for good water flow, etc. It is for these problems that I wrote this instructable.In addition, it is a verifiable fact that the effectiveness of a swamp cooler decreases as the relative humidity increases, not a myth. It is just one of those pesky laws of physics that we haven't been able to overturn yet. At a 106 degree outside to get 70 degree air, you will need to be less then 5% humidity. On the day of your post, you had a low of 7% humidity in Acton, so it seems probable that you would be blowing approximately 72-74 degree air with an outside temp of 106. If, for example, you were at 35% humidity on that day, you would only be blowing 88 degree air.This is why you don't see swamp coolers in the southeast US very often. It becomes more economic to just use a normal air conditioner when the humidity is up over 25% during the heat of the day.Hopefully this explanation will be helpful to people. You can google how swamp coolers work for some good articles on the subject.

You can do that. The other part of the trick is to get better distribution of the water at the top of the pads with more output hoses. Two pumps allows you to add the thermostat on #2, that is addressed in the comments early on.

I have had both, (here in Utah) The Master cool works a little bit better, but they are expensive and you have to replace the cardboard insert things every couple years and they are also expensive. I modded the master cool to spray more water also, but I did it a little differently, but same basic idea.